Methods to compensate for noise in a wireless communication system

• US 20070036176A1
• Filed: 10/23/2006
• Published: 02/15/2007
• Est. Priority Date: 10/30/1998
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Chen, Feng, Denney, Lisa, Samueli, Henry, Lu, Fang, Min, Jonathan, Jones, Christopher, Quigley, Thomas, Nazareth, Sean
• Granted Patent: US 7,821,954 B2
• Time in Patent Office: Days
• US Class Current: 370/468
• CPC Class Codes: H04B 1/1027 assessing signal quality or detecting noise/interference for the received signal
• CPC Class Codes: H04B 1/1036 with automatic suppression of narrow band noise or interference, e.g. by using tuneable notch filters H04B1/123 takes precedence; filter circuits H03H
• CPC Class Codes: H04J 3/0655 using timestamps
• CPC Class Codes: H04J 3/0682 by delay compensation, e.g. by compensation of propagation delay or variations thereof, by ranging
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0045 Arrangements at the receiver end
• CPC Class Codes: H04L 1/0061 Error detection codes
• CPC Class Codes: H04L 1/203 Details of error rate determination, e.g. BER, FER or WER
• CPC Class Codes: H04L 12/2801 Broadband local area networks
• CPC Class Codes: H04L 2025/03808 Transmission of equaliser coefficients
• CPC Class Codes: H04L 25/03019 adaptive, i.e. capable of adjustment during data reception
• CPC Class Codes: H04L 25/03057 with a recursive structure H04L25/03031 takes precedence
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end
• CPC Class Codes: H04L 27/0014 Carrier regulation of chaotic carriers H04L27/001; for multicarrier receivers H04L27/2657
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems
• CPC Class Codes: H04L 27/34 Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
• CPC Class Codes: H04L 41/142 using statistical or mathematical methods
• CPC Class Codes: H04L 5/003 Arrangements for allocating sub-channels of the transmission path
• CPC Class Codes: H04L 5/1446 of transmission speed
• CPC Class Codes: H04W 72/542 : using measured or perceived quality
• CPC Class Codes: Y02D 30/50 : in wire-line communication networks, e.g. low power modes or reduced link rate

Abstract

A number of features for enhancing the performance of a communication system, in which data is transmitted between a base station and a plurality of subscriber stations located different distances from the base station, are presented. The power transmission level, slot timing, and equalization of the subscriber stations are set by a ranging process. Data is transmitted by the subscriber stations in fragmented form. Various measures are taken to make transmission from the subscriber stations robust. The uplink data transmission is controlled to permit multiple access from the subscriber stations.

Claims

1. A method of compensating for conditions on an uplink channel from a plurality of subscriber stations to a base station, the method comprising:

transmitting on a downlink channel from the base station to a plurality of subscriber stations MAP messages that assign time slots in which subscriber stations may transmit signal bursts on the uplink channel, the MAP messages including idle slots that are assigned to no subscriber stations;

monitoring conditions on the uplink channel during the idle slots;

compensating for the monitored conditions on the uplink channel; and

receiving at the base station signal bursts on the uplink channel after such compensation.

2. The method of claim 1, wherein monitoring the conditions includes sensing noise on the uplink channel during the idle slots.

3. The method of claim 2, wherein compensating for the monitored conditions includes adjusting coefficients of a notch filter to compensate for the sensed noise on the uplink channel during the idle slots.

4. The method of claim 3, wherein compensating for the monitored conditions further includes adjusting a feedback filter of a decision feedback filter in series with the notch filter to have the same coefficients as the notch filter to compensate for its distortion.

5. The method of claim 4, further comprising:

receiving on the uplink channel a ranging signal from a subscriber station;

adjusting coefficients of a feedforward filter of the decision feedback filter responsive to the received ranging signal to compensate for intersymbol interference on the uplink channel; and

transmitting the adjusted coefficients on a downlink channel to the subscriber station for the purpose of pre-equalization.

6. The method of claim 5, wherein transmitting the MAP messages and transmitting the adjusted coefficients are performed on the same channel.

7. A method of compensating for conditions on an uplink channel from a plurality of subscriber stations to a base station, the method comprising:

compensating for noise on an uplink channel;

receiving on the compensated uplink channel a ranging signal from a subscriber station of the plurality of subscriber stations;

adjusting filter coefficients to compensate for intersymbol interference on the uplink channel responsive to the received ranging signal; and

transmitting the adjusted coefficients on a downlink channel to the subscriber station for the purpose of pre-equalization of the uplink channel.

8. The method of claim 7, wherein adjusting the filter coefficients includes adjusting coefficients of a feedforward filter of a decision feedback filter.

9. The method of claim 8, wherein compensating for the noise includes adjusting the coefficients of a notch filter in series with the decision feedback filter.

10. The method of claim 9, wherein compensating for the noise includes adjusting a feedback filter of the decision feedback filter to have the same coefficients as the notch filter to compensate for its distortion.

11. The method of claim 10, further comprising:

transmitting on a downlink channel from the base station to the subscriber stations MAP messages that assign time slots in which subscriber stations may transmit signal bursts on the uplink channel.

12. The method of claim 11, wherein transmitting the MAP messages and transmitting the adjusted coefficients are performed on the same channel.

13. A method of compensating for noise in a wireless communication system, comprising:

transmitting a MAP message via a downlink channel from a base station to at least one subscriber station, the MAP message assigning time slots during which the at least one subscriber station is allowed to transmit signal bursts via an uplink channel to the base station, the MAP message including at least one idle slot not assigned to any subscriber station;

sensing noise associated with the uplink channel during the at least one idle slot; and

adjusting a filter coefficient based on the noise to suppress the noise in signal bursts received via the uplink channel.

14. The method of claim 13, further comprising:

compensating for distortion caused by adjusting the filter coefficient using a feedback equalization technique.

15. The method of claim 13, further comprising:

receiving a ranging signal via the uplink channel from a subscriber station;

adjusting coefficients of a feedforward filter in response to receiving the ranging signal to compensate for intersymbol interference associated with the uplink channel; and

transmitting the adjusted coefficients of the feedforward filter via the downlink channel to the subscriber station to facilitate pre-equalization.

16. The method of claim 15, wherein transmitting the MAP messages and transmitting the adjusted coefficients are performed on the same channel.

17. A method of compensating for noise in a wireless communication system, comprising:

transmitting a ranging signal to a base station;

receiving pre-equalization coefficients from the base station based on the ranging signal; and

performing a pre-equalization operation to compensate for noise associated with a subscriber station based on the pre-equalization coefficients.

18. The method of claim 17, wherein the pre-equalization coefficients represent frequency shaping necessary to compensate for the noise that is unique to the subscriber station.